Semiconductor laser with low relative intensity noise of individual longitudinal modes and optical transmission system incorporating the laser

Abstract

A semiconductor laser comprises an electrically isolated active section and at least one noise reducing section and operates on a ground state transition of a quantum dot array having inhomogeneous broadening greater than 10 nm. The laser preferably emits more than 10 optical modes such that a total relative intensity noise of each optical mode is less than 0.2% in the 0.001 GHz to 10 GHz range. The spectral power density is preferably higher than 2 mW/nm. An optical transmission system and a method of operating a quantum dot laser with low relative intensity noise of each optical mode are also disclosed.

Description

REFERENCE TO RELATED APPLICATIONS[0001]This application claims one or more inventions which were disclosed in Provisional Application No. 61 / 119,414, filed Dec. 3, 2008, entitled “SEMICONDUCTOR LASER WITH LOW RELATIVE INTENSITY NOISE OF INDIVIDUAL LONGITUDINAL MODES”. The benefit under 35 USC §119(e) of the U.S. provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference.[0002]This application is also a continuation-in-part of co-pending patent application Ser. No. 11 / 938,472, filed Nov. 12, 2007, entitled “OPTICAL TRANSMISSION SYSTEM, which claims one or more inventions which were disclosed in Provisional Application No. 60 / 867,952, filed Nov. 30, 2006, entitled “OPTICAL TRANSMISSION SYSTEM”, and is a continuation-in-part of patent application Ser. No. 11 / 295,943, filed Dec. 7, 2005, entitled “LASER SOURCE WITH BROADBAND SPECTRUM EMISSION”, now U.S. Pat. No. 7,561,607, issued Jul. 14, 2009, and patent application Ser. No....

AI Technical Summary

Benefits of technology

[0008]A multimode edge-emitting semiconductor laser has low relative intensity noise (RIN) of individual longitudinal modes. The active region of the laser is based on an inhomogeneously broadened array of self-organized quantum dots (QDs). The laser includes an active section and at least one integrated noise reducing section, where the active section and the noise reducing sections are electrically isolated. The noise reducing section provides mode coupling and synchronization.

[0009]The laser emits a plurality of optical modes such that the relative intensity noise of each optical mode is less than 0.2% in the 0.001 GHz to 10 GHz range. In one embodiment, the average optical power per channel is more than 2 mW. The RIN of each longitudinal mode is sufficient to obtain a low bit error rate at high modulation speeds.

[0010]In another embodiment, the total RIN is less than 0.1% for at least ten optical modes. In yet another embodiment, the total RIN is less than 0.2% for at least 48 optical modes, and their intensity distribution is very uniform and varies by 30% or less.

[0011]In a preferred embodiment, the longitudinal modes are used as independent information channels in a multi-channel optical transmission system. An optical transmission system includes at least one laser that provides a plurality of low RIN optical ...

Problems solved by technology

The complexity of fabrication of a DFB laser 901 results in its high cost, which is further multiplied by the number of lasers 901 to be integrated.

This makes it difficult to build an array of single-frequency lasers 901 with pre-se...

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